Corrosion-inhibiting and fingerprintremoving composition



CORROSION-INHIBITING AND FINGERPRINT- REMOVING COMPOSITION Allen E. Brehm, Griflith, Ind and Albert W. Lindert, Homewood, Ill., assign'ors' to Standard Oil Company, Chicago, 111., a corporation of Indiana No Drawing. Application July 16, 1954, Serial No. 443,968

15 Claims. (or. 252-161 This invention relates to corrosion inhibiting compositions, and more particularly pertains to rust preventive compositions adapted to remove salt and acids which cause corrosion and to prevent and/or inhibit salt-type corrosion, particularly fingerprint corrosion of metals.

Salt-type corrosion of metals is so named because corrosion of the metal is partially due to adherent inorganic salt particles, rather than to external fluid agencies. A particular form of salt-type corrosion is the so-called fingerprint corrosion which generally follows the handling of metal stocks and is in some way related to the acids and salt deposited on the metal or perspiration transferred from the hands of the handlers of such metal stocks. This salt-type or fingerprint corrosion is particularly difficult to avoid or inhibit in spite of the fact that its general nature has been recognized by metal workers and others for many years. This type of corrosion problem has persisted in spite of extensive developments in the field of slushing compounds. Slushing compounds are rust preventives and are usually classified as liquid or oils or solid or greases from the standpoint of appearance, handling and service properties. Slushing compounds appear to exert a protective eifect on metal surfaces in P t y o m n an adh ent coating and i pa y the effects which may be attributed to anti rust agents, dissolved or dispersed in such composition. For reasons not clearly understood, it has been found that saltetype or fingerprint corrosion can continue undera protective coating of slushing compounds numerous instances where the metal has been handled manually before the application of the slushing compound. The presence of a salt-type fingerprint corrosion can be to a large extent combatted by using corrosion inhibiting compositions having the properties of (1) readily displacing water, (2) removing substantially all adherent corrosive substances, such as salts and acids present in human per: spiration, and (3) suppressing or inhibiting further corrosive influences. Toa large extent the problem of preventing and/or removing fingerprint corrosion has been successfully accomplished by'the use of slushing compositions of the type described by Donald I. Walker and Edgar A. Dieman in U. S, Patent 2,598,949. However, under certain conditions, for' unlgnown reasons, completely satisfactory results are not alwaysattai-ned by the use of such compositions.

It is an object of the present invention to provide an improved composition for PIventing and/or inhibiting corrosion of metals. Another object of the invention is to provide compositions especially adapted to displace water and remove acids and salts in combatting corrosion: of metals. Still another object of the invention is to. provide slushing compositions for protecting metal surfaces against fingerprint or salttype corrosion. A still further object of the invention is to provide a stable composition which is adapted for displacing water. and which possesses excellent properties for prevention and/or inhibiting corrosion of rrietal s, particularly 'salt t ype or fingerprint-type corrosion. -Othrobjectsand advantages nited States Patent 2,796,408 Patented June 18, 1957 ice 2 of the invention will become apparent from the following description thereof.

We have discovered that the foregoing objects can be attained by employing compositions having the following ingredients in the following approximate proportions, by Weight:

The salt-reinoving agent which assists in the complete removal of residual salts deposited on the metal surfaces and which cause salt-type or fingerprint-type corrosion are compounds having the general formula where R is an alkyl radical having from about 10 to about 24 carbon atoms, and x is a number of l to 4. Such compounds are alkyl thioethers of a monobasic aliphatic carboxylic acid having not more than 4 carbon atoms in the acid radical wherein the etherfying group is attached to a carbon atom of a carboxylic acid not in the carboxyl radical, for example alpha alkyl thioether of acetic acid, beta alkyl thioether of propionic acid, etc. Examples of suitable compounds of the above general formula are decyl thioether of acetic acid, dodecyl thioether of acetic acid, decaoctyl thioether of acetic acid, cetyl thioether of acetic acid, dodecyl thioether of pro-p pionic acid, cetyl thioether ,of propionic acid and similar butyric acid derivatives.

The alkaline earth soaps of preferentially oil-soluble sulfonic acids used in the above formulation are preferably the soaps of sulfonic acids obtained in the treatment of hydrocarbon oils, such as petroleum lubricating oils with strong sulfuric acid, such as concentrated sulfuric acid of at least about strength, or fuming sulfuric acid. The alkaline earth soaps of preferentially oilsoluble sulfonic acids, such as those obtained by the sulfonation of olefin polymers having at least about 22 carbon atoms in a molecule or those obtained by the sulfonation of alkylated aromatics having at least about 19 carbon atoms, can also be used.

Preferentially oil-soluble petroleum sulfonic acidsare those obtained in the treatment of petroleum oils to obtain highly refined products of the type of technical insulating oils, turbine oils, medicinal white oils, technical white oils, etc., in which the petroleum oils are treated successively with a number of portions of concentrated sulfuric acid, i. e. above about 95% strength, or fuming sulfuric acid. A variety of sulfur-containing compounds are formed by chemical reaction of the sulfuric acid upon the oil, including sulfonic acids, organic esters of sulfuric acid, and partial esters of sulfuric acid. Most of these compounds are relatively insoluble in the oil under treating conditions and separate from the oil together with unreacted sulfuric acid as a sludge, which is separated from the oil after each treatment. The sulfuric acid is usually added in dumps of about one-half pound per gallon of oil, the total quantity of acid added depending upon the oil being treated and the final product. Usually, rom a ou th ee pounds to. about n ne pounds, of sulf r acid per gallon of oil are'used. Some of the sulfonic acids resulting from the treatment of the oil with'the sulfiu a id are prefer t ally oil-solub e and rema n in. the oil layer after removal of the acid sludge. The sulfonic acids in the acid-treated oil can be extracted therefrom with an alcohol of 60-70% strength, and the extracted sulfonic acids neutralized with a basic alkaline earth compound, such as for example, lime. Because of the characteristic mahogany color of the sulfonates they are known as mahogany soaps in the petroleum art. While the majority of the preferentially oil-soluble sulfonates are obtained from the acid-treated oil, there can be recovered from the acid sludge by suitable solvents, preferentially oil-soluble sulfonates or sulfonic acids. The term preferentially oil-soluble sulfonates therefore includes the oil-soluble sulfonates recovered from the acidtreated oil and the acid sludge.

While any of the preferentially oil-soluble alkaline earth sulfonates, such as calcium, barium, or strontium sulfonates can be used, we prefer to employ those obtained from the preferentially oil-soluble sulfonic acids having combining molecular weights in the range of from about 350 to about 525, and preferably those in the range of from about 420 to about 500. The sulfonic acid soaps obtained in the manner described contain from about 30% to about 60% sulfonate, from about 30% to about 60% oil, up to about 2.0% water, and less than 0.5% inorganic salts.

The calcium soaps of the preferentially oil-soluble petroleum sulfonic acids or mahogany acids are preferred, and the preparation thereof is illustrated by the following example: A Mid-Continent petroleum distillate having a Saybolt Universal viscosity at 100 F. of between 200 seconds and 230 seconds, is treated with 6 pounds of. fuming sulfuric acid per gallon of oil in one-half pound dumps. After the separation of the acid sludge, the acidtreated oil is treated with a suitable alcoholic, for example, ethyl alcohol of about 60% strength to remove crude preferentially oil-soluble petroleum sulfonic acids. The alcc holic layer containing the crude sulfonic acids is then treated with lime, preferably in the form of a lime slurry to neutralize the sulfonic acids. The mixture is allowed to settle, the alcohol layer containing the calcium mahogany soap is drawn off and then distilled to remove the alcohol therefrom. The resultant calcium soap of the preferentially oil-soluble petroleum sulfonic acids is usually of 70% to 80% concentration in unreacted oil. To facilitate the handling of the soap, it is preferred to further dilute the soap with a petroleum oil of suitable viscosity to a concentration of about 3540% The hydrocarbon oil content of the composition is that present in the petroleum sulfonate compound, and, if desired, added as additional oil. As noted above, the petroleum sulfonate product contains 6065% hydrocarbon oil of suitable viscosity. Usually oils of from about 50 to about 1000 seconds Saybolt Universal viscosity at 100 F. are used.

The hydrocarbon solvent is one boiling in the range between about 100 F. and about 650 F. Hydrocarbon solvents which we have found suitable for the purposes herein described are preferably petroleum distillates, such as petroleum ether, gasoline, naphthas or kerosenes of the desired distillation range. Of the hydrocarbon oil fractions it is preferred to employ a solvent boiling in the gasoline to kerosene boiling range, and particularly good results are obtained by employing a heavy naphtha boiling in the range of between about 300 F. and 400 F. at atmospheric pressure, such as for example, the hydrocarbon solvent commonly known as Stoddard Solvent.

In order to prepare clear, bright and stable compositions, and yet produce compositions especially adapted to penetrate and displace water on the surfaces of metals for the removal of corrosive substances thereon, we have found it necessary to employ as a mutual solvent for the water and oil, as well as an aid in fingerprint removal, a water-soluble oxygenated organic solvent having a flash point above about 100 F., particularly aliphatic alcohols, polyhydric alcohols, ketones, and ethers. Examples of suitable water-soluble oxygenated organic solvents are diacetone alcohol, diisobutyl ketone, ethyl butyl ketone,

n-butyl alcohol, Z-ethyl-butanol, diethyl Carbitol, dibutyl Carbitol, butyl Carbitol, hexylene glycol, propylene glycol, ethylene glycol, Carbitol, Cellosolve, butyl Cellosolve, etc. Carbitols are ethers of diethylene glycol and Cellosolves are ethers of ethylene glycol marketed by Carbide and Carbon Chemicals Corporation.

The preferentially water-soluble sulfonates used in the herein-described composition is employed as a coupling or wetting agent and is suitably selected from a variety of compounds, including various sulfonated fish or animal oils, vegetable oils, fats and waxes, and preferentially water-soluble alkali metal soaps of petroleum sulfonic acids having molecular weights in the range of from about 400 to 430. The sulfonated fish, animal, vegetable oils, fats or Waxes are rendered preferentially watersoluble by being partially or wholly neutralized with a caustic solution, for example, sodium, potassium or ammonium hydroxide. Preferred coupling agents are a water-soluble sulfonated castor oil prepared by adding to a sulfonated castor oil suificient caustic solution to neutralize any residual or unreacted sulfuric acid and wholly or partially neutralizing the sulfonated fatty acid content, and alkali metal soaps of petroleum sulfonic acids of about 400 to 430 molecular weight and which are more water-soluble than the alkaline earth sulfonates used in the composition.

The following examples will serve to illustrate compositions of the present invention; in which the proportions are Weight percents:

Example No.

Preferen tially oil-soluble calcium mahogany soap 13.0 15. O 23. 5 23. 5 Sodium mahogany soap 3.0 3.0 3. 0 3.0 Oetyl thioether of acetic acid 0. 5 0. 5 0. 5 0. 5 Butyl Garbitol 1 6.0 6. 0 5. 0 Hexylcne glycol 7. 0 Stoddard Solvent-- 58.0 58. 0 56. 0 58. 0 Hydrocarbon Oil 15. 5 13. 5 6.0 5.0 Water 4. 0 4. 0 5. 0 5. 0

*Sulfonic acid molecular weight-470. *Sulfonie acid molecular weight-430.

1 37% soap; 63% oil.

2 50% soap; 50% oil.

3 Diethylene glycol monobutyl ether.

4 Saybolt Universal Viscosity at F.180l85 seconds.

The composition of this invention meets the requirements of Government specification as well as requirements for commercial use. The tests, among others, which the formulation has been found to pass and which are required by the above specification are:

Stability.--There shall be no separation into layers when examined after alternately cooling to 40 F. for 8 hours and heating to F. for 16 hours three times, followed by inverting the container and returning to the original position six times and standing one hour.

Flash point.-100 F. minimum.

Fingerprint rem ovaL-The compound shall remove all traces of fingerprint contamination. Steel panels are printed with synthetic fingerprint solution by means of a rubber stopper and dried in an oven. The panels are slushed for two minutes in the fingerprint remover. The fingerprint remover is removed by slushing in solvent and the panels are exposed 24 hours in a 100% static humidity chamber for 24 hours at 77 F.

Fingerprint suppressi0n.-The compound shall prevent corrosion by fingerprint contamination. Test panels are printed as above, using synthetic fingerprint solution diluted to /3 the strength, as used above, using methanol as the diluent. The panels are laid flat and .05 ml. of the remover composition dropped on the printed area and allowed to dry overnight. The panels are then exposed to 100% humidity as above.

Pr0tecti0n.Steel surfaces shall be protected by the compound. Steel panels are dipped in the compound for one minute and allowed to drain overnight. They are then exposed for 7 days in a humidity cabinet meeting Specification JAN-H792 (100% humidity, 120 F.).

Remvabilizy.The fingerprint remover shall be completely removed from the panels after the panels have been immersed in the fingerprint remover and then slushed in solvent for two minutes. No visible film shall remain after the solvent has evaporated.

C0rr0sion.-The compound shall not produce corrosive effects as evidenced by weight loss beyond certain limits to steel, brass, zinc, lead, and aluminum. The compound, with weighed test panels submersed, is held at 130 F. for seven days, after which the panels are carefully washed free of compound and weighed.

Handling.--The compound shall protect against fingerprint corrosion. Clean steel panels are dipped in the compound for one minute. One panel is allowed to drain 30 minutes and a second panel for 16 hours. After draining, the panels are printed with synthetic fingerprint solution applied by means of a rubber stopper. The panels are then exposed in a 100% static humidity for 24 hours.

The above briefly described tests are described in detail in Government Specification MIL-R-l5074. The formulation of Example I, in particular, meets all of the above tests. The products of Examples II-IV while not meeting all of the requirements of MIL-R-15074, are nevertheless very satisfactory products for commercial use.

Unless otherwise stated, percentages given herein and in the appended claims are weight percentages.

While the present invention has been described by reference to specific embodiments thereof, these are given by way of illustration only and it is not intended to limit the invention thereto which includes within its scope such modificationsand variations as come within the spirit of the appended claims.

We claim:

1. A corrosion-inhibiting and fingerprint-removing composition comprising from about 2.0% to about 10.0% of a preferentially oil-soluble alkaline earth sulfonate, from about 0.5% to about 5.0% of a preferentially watersoluble sulfonate, from about 0.1% to about 1.0% of an alkyl thioether of a mono-basic aliphatic carboxylic acid having not more than 4 carbon atoms in the acid radical and from about to about 24 carbon atoms in the alkyl radical of the alkyl thioether group, from about 3.0% to about 12.0% of a water-soluble oxygenated organic solvent having a flash point above about 100 F., from .about 40.0% to about 65.0% of a hydrocarbon solvent having a boiling point of from about 100 F. to about 650 F., from about 5.0% to about 25.0% of a hydrocarbon oil having a Saybolt Universal viscosity at 100 F. of from about 50 to about 1,000 seconds, and from about 2.0% to about 8.0% water.

2. A composition as described in claim 1, in which the preferentially oil-soluble alkaline earth sulfonate is an alkaline earth soap of a preferentially oil-soluble petroleum sulfonic acid.

3. A composition as described in claim 1, in which the preferentially oil-soluble sulfonate is a calcium soap of a preferentially oil-soluble petroleum sulfonic acid.

4. A composition as described in claim 1, in which the preferentially water-soluble sulfonate is a preferentially water-soluble alkali metal petroleum su lfonate.

5. A composition as decribed in claim 1, in which the preferentially water-soluble sulfonate is a preferentially water-soluble sodium petroleum sulfonate.

6. A composition as described in claim 1, in which the water-soluble sulfonate is a water-soluble sulfonated castor oil.

7. A composition as described in claim 1, in which the 0 alkyl thioether of a mono-basic aliphatic carboxylic acid is cetyl thioether of acetic acid.

8. A composition as described in claim 1, in which the alkyl thioether of a mono-basic aliphatic carboxylic acid is dodecyl thioether acetic acid.

9. A composition as described in claim 1, in which the alkyl thioether of a mono-basic aliphatic carboxylic acid is cetyl thioether propionic acid.

10. A composition as described in claim 1, in which the water-soluble oxygenated solvent is diethylene glycol monobutyl ether.

11. A composition as described in claim 1, in which the water-soluble oxygenated solvent is hexylene glycol.

12. A composition as described in claim 1, in which the hydrocarbon solvent is a petroleum naphtha having a distillation range of from about 300 F. to about 400 F.

13. A corrosion-inhibiting and fingerprint-removing composition comprising the following ingredients in approximately the following proportions, by weight.

Percent Preferentially oil-soluble calcium mahogany soap 14. A corrosion-inhibiting and fingerprint-removing composition comprising the following ingredients in approximately the following proportions, by weight.

Percent Preferentially oil-soluble calcium mahogany soap (37% soap, 63% oil) 23.5 Sodium mahogany soap soap, 50% oil) 3.0 Cetyl thioether of acetic acid 0.5 Hexylene glyc l 7.0 Stoddard solvent 56.0 Hydrocarbon oil (180-l85 SUS at 100 F.) 5.0 Water 5.0

15. The method of removing fingerprints from metal surfaces and inhibiting the corrosion of such surfaces, comprising applying to the surfaces of metal objects which are normally manually handled a composition comprising from about 2.0% to about 10.0% of a preferentially oil soluble alkaline earth esulfonate, from about 0.5% to about 5.0% of a preferentially water-soluble sulfonate, from about 0.1% to about 1.0% of an alkyl thioether of a mono-basic aliphatic carboxylic acid having not more than 4 carbon atoms in the acid radical and from about 10 to about 24 carbon atoms in the alkyl radical of the alkyl thioether group, from about 3.0% to about 12.0% of a water-soluble oxygenated organic solvent having a flash point above about F., from about 40.0% to about 65 .0% of a hydrocarbon solvent having a boiling point of from about 100 F. to about 650 F., from about 5.0% to about 25.0% of a hydrocarbon oil having a Saybolt Universal viscosity at 100 F. of from about 50 to about 1,000 seconds, and from about 2.0% to about 8.0% water.

References Cited in the file of this patent UNITED STATES PATENTS 2,382,699 Duncan Aug. 14, 1945 2,474,604 Wasson June 28, 1949 2,517,636 David Aug. 8, 1950 2,598,949 Walker June 3, 1952 2,677,618 Dieman May 4, 1954 

1. A CORROSION-INHIBITING AND FINGERPRINT-REMOVING COMPOSITION COMPRISING FROM ABOUT 2.0% TO ABOUT 10.0% OF A PREFERENTIALLY OIL-SOLUBLE ALKALINE EARTH SULFONATE, FROM ABOUT 0.5% TO ABOUT 5.0% OF A PREFERENTIALLY WATERSOLUBLE SULFONATE, FROM ABOUT 0.1% TO ABOUT 1.0% OF AN ALKYL THIOETHER OF A MONO-BASIC ALIPHATIC CARBOXYLIC ACID HAVING NOT MORE THAN 4 CARBON ATOMS IN THE ACID RADICAL AND FROM ABOUT 10 TO ABOUT 24 CARBON ATOMS IN THE ALKYL RADICAL OF THE ALKYL THIOETHER GROUP, FROM ABOUT 3.0% TO ABOUT 12.0% OF A WATER-SOLUBLE OXYGENATED ORGANIC SOLVENT HAVING A FLASH POINT ABOVE ABOUT 100* F., FROM ABOUT 40.0% TO ABOUT 65.0% OF A HYDROCARBON SOLVENT HAVING A BOILING POINT OF FROM ABOUT 100* F. TO ABOUT 650* F., FROM ABOUT 5.0% TO ABOUT 25.0% OF A HYDROCARBON OIL HAVING A SAYBOLT UNIVERSAL VISCOSITY AT 100* F. OF FROM ABOUT 50 TO ABOUT 1,000 SECONDS, AND FROM ABOUT 2.0% TO ABOUT 8.0% WATER. 